Mooring failures

[lw395]

...
One of my pet peeves that I have been ranting bout for years is that pendant failures are often incorrectly assigned to chock chafe when in fact many of them part due to anchor chafe from anchors left on bow rollers. Seeing as I live right near the local harbor which has over 1200 moored boats I have plenty of access to mooring failures.

Some of you who frequent the US sailing forums will remember my many rantings about folks leaving anchors on their bows, in exposed mooring fields, during rough weather. If your mooring field has the fetch to build waves that can pitch the bow of your boat then it is rather rude & inconsiderate to the boaters around you, who may get hit by your drifting boat to not remove your anchor when a blow is expected. Many times chafe comes from the chocks but after motoring around the anchorage the morning after this short storm I saw that most of the chafe was anchor related. This is not the first nor the last storm I have or will monitor for mooring failures.


For the rest of the article and a LOT more photos you can read it here:

Mooring Preparations & Precautions (LINK)


For some time now I had been trying to capture the "moment" on film to really drive the point home about REMOVING your anchor if a storm is coming. Some folks actually get it, but still many don't. I think this Island Packet is a PRIME example of "my anchors are protected by a bow sprit, I don't need to remove them" line of reasoning.


PLEASE, if not for your boat, think of the others around you and what your boat would do in 30+ knots drifting through an anchorage after the anchor has sliced through the pendants. I watched it happen in real time, it leaves a pit in your stomach. Thank god MOST moorings in Falmouth are dual pendant rigged. This boat owner came very close to owning a pile of off white fiberglass splinters..


Mooring Preparations & Precautions (LINK)

That was always going to happen.
Looks fairly exposed, a bit like my old mooring.
A lot of people do not seem to appreciate how flat an angle the strop may go to in a blow, especially with some waves about.
The strop would have been well clear of those anchors in benign conditions.
It might have worked better with a much shorter strop.
Boats with bobstays are a bit problematic, it will always chafe.

Regarding 3 -strand warps unlaying, it's true I've got one in the garage somewhere. However I don't think the cure is to use different rope, but rather to get a swivel that works! Braided rope will be weakened by winding it up too! I have seen small cruisers end up very bow down due to winding up the whole mooring riser. I think the swivel is best placed between the buoy and the boat where it isn't corroding and can be inspected easily. Motorcycle aerosol chain wax is the stuff for lubing such swivels BTW!

 

[prv]

Boats with bobstays are a bit problematic, it will always chafe.

Agree - I always slack off and trice up my bobstay on a mooring or at anchor, even for one night. Obviously a bit of a problem for sloop-headed boats where the bobstay is more structural and can't easily be let go. I'm told that threading plastic tube onto it helps, as the tube rolls round instead of letting the line saw against the chain or wire.

Pete

 

[SHUG]

Someone has to say it.............many chandlers stock cheap inferior quality shackles and swivels from the Far East which are not fit for purpose either in the quality of the material or in the thickness of the galvanising.
Who makes the genuine article in the UK ?????

 

[Tradewinds]

Someone has to say it.............many chandlers stock cheap inferior quality shackles and swivels from the Far East which are not fit for purpose either in the quality of the material or in the thickness of the galvanising.
Who makes the genuine article in the UK ?????

You could try these people

http://www.eyecochain.com/shackles.asp

 

[aquaplane]

I may have got the wrong impression but most of the boats I have seen tied up at the Wardens seem to have the mooring buoy still attached indicating that it's the riser that's failed.

When my mooring failed it was the swivel that gave up and the riser links were very thin where they had worn. The strop was in good condition.

I do look at my mooring much more than I used to. I am lucky that it's only 6' deep and I can lift it enough to get the swivel to the surface. Perhaps another swivel under the buoy would be a good idea but I didn't want to add another weak point.

It's time I went to check on the strops.

 

[sarabande]

Cosalt make tested and certificated shackles for the fishing and oil industry. They ain't cheap, but they are tough.

http://www.cosalt.com/products-services/products/liftingandinspection.ashx

 

[caiman]

During my time as a local mooring contractor,I had two boats go 'walkabout'.(both retrieved undamaged and none the worse)One was due to discarded fishing line stopping the swivel from turning, and undoing the splice(five tucks and tapered),and the other was due to a brand new tested chain failing on a weld.In my experiance,I found that having too long a bridal causes the rope to 'popple'.
For all things moorings,I have never had a problem with anything from Bradney Chains.My present mooring is all from Bradney.They also provide a nice mooring guide on thier website,which,with one or two mods,are the guidelines I use.
Cheers

 

[Seajet]

I've had a half-tide swinging mooring in Chichester Harbour since 1978.

A few observations;

The vast majority of failures I've seen have been swivels.

In the 1987 October Hurricane, many boats were driven ashore complete with their mooring sinkers; since then a lot more attention has been paid by our club, with very significantly heavier sinkers and chains.

There is a known problem of 'accelerated steel corrosion' in Chichester Harbour.

I have found it extremey informative to stay on the boat and look around when the tide is coming, going or out, and suggest more people should do this, it's surprising to see some of the things boats do; it also might help avoid their boats colliding with mine when just afloat on a changing wind !

An example of boat movement in changeable wind when just afloat;

 

[ukmctc]

Many years ago in Cromarty I put in my own two moorings, the local club moorings at least 2 used to come ashore every year. I used a very large rear tractor tyre, filled with seahard cement, With 2" steel bar, attached to 27 mm stud link chain (10mtrs) attached to 10mtr riser (seasteel rope) with large bouy. Advised by local Chandlers Gaelforce Marine, Still there 15 years on.

 

[Resolution]

Maine Sail
Great photos. Why was the Island Packet pitching so heavily when the dinghy with outboard in your foreground was staying pretty level?

 

[pyrojames]

As the OP says:
"Conventional 3-strand rope is not used for swinging boat-ropes/bridles because it can unlay and splices then fail…."

.....which probably refers to accepted practice and experience in Jim Izzard's neck of the woods, but I wouldn't know as I haven't read the book, yet.

I find it difficult to conceive a bridle that would unlay...

 

[Lakesailor]

I am glad you said that.
I would have expected some sense from you.
These wild assumptions that a decent 3 strand bridle will fall to bits with a bit of rough weather had me baffled.
I use a pair of 3 strand strops and change them every 2 years. None have ever shown any sign of falling to bits.
The lakes can produce nasty chop and wind shifts to wind-up moorings several times a day, not just twice.

 

[tyce]

I am glad you said that.
I would have expected some sense from you.
These wild assumptions that a decent 3 strand bridle will fall to bits with a bit of rough weather had me baffled.
I use a pair of 3 strand strops and change them every 2 years. None have ever shown any sign of falling to bits.
The lakes can produce nasty chop and wind shifts to wind-up moorings several times a day, not just twice.

I have also witnessed 3 strand unwind several times not to far from your neck of the woods (roa island), the wise boat owners now use a back up stainless chain bridle, i use octoplait.
The main cause of the unwinding has been due to double stropping, one strop has managed to wind round the other and it all goes down hill from there.

 

[caiman]

I guess that it just goes to show we all sail in different waters,and what works in one area,may,or may not work in another.I suppose the answer is'do what the locals do'.
Cheers

 

[Lady Campanula]

Perhaps the important point from all this is that pro engineer Jim Izzard's survey of pro contractors' best practices in the West Country will shine a needed light into an area of our boating that has been very much 'by guess and By God'.

My purpose was to provoke interest in the content of the booklet.

Certainly, some of the practices fondly preferred by one pro mooring contractor will differ in detail from that of his rival a few miles away. Sometimes one suspects that money/time or 'we've always done it this way' has a bearing.

What is crystal-clear to me, after reading the book, that we boat owners have a significant gap in our 'know-how and why'. This small book goes far in closing that gap.

Might I recommend to all either a reading of the book, or an email to PBO to print their definitive article on this subject. Either way, it's a cheap way for us to raise our game on this topic.




Oh, and do read Mooring Book Man's comments at #20

 

[pyrojames]

I have also witnessed 3 strand unwind several times not to far from your neck of the woods (roa island), the wise boat owners now use a back up stainless chain bridle, i use octoplait.
The main cause of the unwinding has been due to double stropping, one strop has managed to wind round the other and it all goes down hill from there.

The fact of a double bridle is that the strand can not unlay due to the boat rotating around the mooring. You simply can not get one strand to rotate between the boat and the mooring without the boat passing between the Y of the bridle and the mooring.

It is far more likely that, as the bridle loads and the 3 strand begins to stretch, the rope naturally unlays, and the bridle twists on itself, more symptomatic of an undersized bridle than a poor layout with 3 strand.

I (and most of the moorings in Sydney) used a single 3 strand in tidal waters and variable wind direction without problems. I now use octoplat riser with a 3 strand bridle as back up.

 

[Old Troll]

Old Troll

Thank You Lady Campanula for raising this subject and welcome the booklet on moorings and any subsequent articles. Many interesting points have already been raised.

 

[Bosun Higgs]

No long term experience of swinging moorings myself but a pal who has his 40 footer on one in the south west uses half inch chain inside plastic pipe as the bridle from the boat to the Hippo buoys and this has worked with complete reliability over many years now.

 

[tyce]

The fact of a double bridle is that the strand can not unlay due to the boat rotating around the mooring. You simply can not get one strand to rotate between the boat and the mooring without the boat passing between the Y of the bridle and the mooring.

It is far more likely that, as the bridle loads and the 3 strand begins to stretch, the rope naturally unlays, and the bridle twists on itself, more symptomatic of an undersized bridle than a poor layout with 3 strand.

I (and most of the moorings in Sydney) used a single 3 strand in tidal waters and variable wind direction without problems. I now use octoplat riser with a 3 strand bridle as back up.

Oh ok then i am obviously mistaken by what i have witnessed first hand and bow to your superior knowledge.
Next time i go out and unravel my double strops (connected directly to a swivel and 3.5 metres long and led to port and strbd) i will remind myself that it is merely an illusion and will also mention to the fellow members of my club that their strops never unwound and their boats never really ended up on the beach!

 

[JayBee]

My copy of "Towards Zero Failures...." arrived this morning. I have done no more than glance at the content, but it promises to be a very interesting and informative read. AS far as I know, nothing like it has been published before.

So..... thanks to Jim Izzard for his "not for profit" moorings research and to Lady C for flagging it up.